Gaseous conduction lamp



March 4, 1930.

Q. SCHALLER ET AL GASEOUS QONDUC'I'ION LAMP Filed July 22, 1920 Patented Mar. 4, 1930 UNITED STATES PATENT; OFFICE OTTO SCHALLER, 0F BERLIN-S'UDENDE, AND FRITZ SCHROTER, OF BERLIN-SCHMAJR GENDORF, GERMANY, ASSIGNORS TO SAFETY GAR HEATING & LIGHTING COMPANY,

A CORPORATION OF NEW JERSEY GASEOUS CONDUCTION LAMP Application filed July 22,

This invention relates to gaseous conduction lamps and more particularly to lamps of the above type in which the luminous discharge passing between the electrodes of the lamp serves as a source of illumination.

One of the objects of this invention is to provide a gaseous conduction lamp in which the luminous discharge passing between the electrodes and through the gaseous content of the lamp may be initiated directly at relatively low voltages, for example voltages in the neighborhood of 110 volts such as are used for ordinary lighting circuits. Another obj ect is to provide a lamp construction in which the discharge of metallic particles from the electrodes and hence the undesirable coating of the interior of the glass bulb, tending to render the latter opaque, are effectively minimized. Strongly electro-positive metals such as potassium, sodium, ca'lcium,etc., possess as electrodes a low cathode drop, and lamps manufactured therefrom can therefore glow with the above mentioned voltage as soon as they are started. When so employed as electrodes in a gaseous content such as neon, or

other gases of the argon group however, the

minimum voltage at which the luminous discharge is started has been found to be slightly in excess of the lighting voltage such as 110 volts with which it is desired to operate such lamps. It is an object of this invention to provide a lamp construction in which such metals, characterized by a low discharge of metallic particles, may beemployed and in which the initial required starting voltage is reduced to values within range of ordinary lighting voltages.

a predetermined path and by means of which 1920. SeriaLNo. 398,273.

the lamp may be made to form a luminous character, figure or other object. 7 Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combination ofelements and arrangement of parts as will be exemplified in the structure hereinafter detion a gaseous conduction lamp, certain parts being shown in section to show more clearly certain features of construction.

Referring in detail to Figure '1, we have illustrated diagrammatically a lamp construction in which we employ a suitable'vessel 1, preferably of glass and which may take the form of an ordinary incandescent lamp bulb,

and we have suitably mounted therein a pair of electrodes 2 and 3. The vessel 1 is filled with a suitable gas preferably one of the gases of the argon group, such as neon, argon or krypton for example, and we may employ one or more of such gases. Small volumes of hydrogen added to the gases of the argon group may also be employed as will be hereinafter more clearly described. The electrodes 2 and 3 preferably consist of metals of the alkali metal group or of the alkali earth group and in order to facilitate the initial starting of the luminous discharge therebetween are made of relatively large effective surface and are so arranged that at-least one of the electrodes, preferably the anode, is uniformly distributed with respect to the other electrode, or cathode. Such a uniform distribution of the surface of one electrode with respect to the surface of the other makes possible a uniformly distributed action of the one electrode upon the other and with the proper spacing between the electrodes, we have been enabled to start the luminous discharge in a gaseous content of neon at a voltage as low as 93 volts.

The electrode 2 is preferably made the anode and may take the form of a Wire grid substantially uniformly distributed with respect to the cathode 3, which, as illustrated in Figure 1, may take the form of a disc. The surface of the cathode 3 adjacent to or facing the anode 2 is made of a strongly electropositive metal, for example, one of the groups hereinbefore mentioned and is provided with a base of a metal having a high heat conductivity, the electro-positive electrode metal being mounted upon this base and suitably secured thereto as by means of mercury for example, or other suitable material by which a good electrical and mechanical connection may be made between the two to insure a good electrical and thermal conductivity. Thus, as shown in Fig. 1 of the drawings, in which is illustrated a section taken through the cathode 3 of Fig. 1, 3"? represents the base or supporting portion of the electrode and is composed, for example, of copper which is characterized by a relatively high heat conductivity. The base portion 3 supports the active electrode portion indicated at 3 and, as hereinbefore noted, may be made of any suitable and, preferably, a strongly electro-positive metal. The active portion 3 is in electrical and mechanical connection with the supporting or base portions 3 by means of a coating of mercury, for example, interposed therebetween and forming in effect an interposed connecting amalgam of the two portions of the electrode. The dotted lines 4 and 5 indicate the electrical conductors passing through the vessel 1 by means of which the electrodes 2 and 3 respectively are connected to the source of current.

The uniform distribution of the surface of the anode with respect to that of the cathode results in a uniform electrical ac-' tion by means of which an initial ionization of the gaseous content is readily made to take place and thus to start the luminous discharge at a relatively low voltage. The composite construction of the cathode 3 results in concentrating the heat produced at the cathode within the metallic base of high thermal conductivity and hence relieves the alkali metal face of thefcathode from being subjected to temperatures which may cause its vaporization. .The vaporization of the metal and hence the segregation of metallic particles therefrom are effectively minimized so that the precipitation of metallic particles upon the interior surface of theglass bulb is reduced to a minimum.

In Figures 2, 3 and 4 we have illustrated in each instance a cathode 3 constructed as described in connection with Figure 1 and in which the cathode 3' is iven an desired form, as for example the letter N. As is shown in Figure 2 the anode 2 may be made of a single wire of a form coinciding substantially with that of the cathode 3 and it will be noted that the anode 2 is so formed and placed with respect to the cathode that its efiective action upon the latter is substantially uniformly distributed. In Figure 3 the anode 2 is shown as formed of a wire and zigzagged so as to bring about a more uniform distribution of the electrical action of one electrode upon the other. In Figure 4 the anode 2 may take the form of a wire grid. The luminous discharge between the two electrodes is thus restricted or guided in a path of predetermined cross section, and the cross section and hence the luminous discharge may be given any form or shape desired, and the, anode construction offers substantially no hindrance to the passage of light rays from the character-forming luminous discharge path.

Referring now to Figure 5 we have shown a vessel 1 preferably of glass and of the form ordinarily given incandescent lamp bulbs provided at its base with an inwardly extending tubular pillar 11 upwardly extended to form a post 6. The post 6 is provided with a collar 12 forming a support for the cathode 3, which may be constructed as hereinbefore described and which in the embodiment herein illustrated is given a substantially conical or parabolic form. Moreover, the cathode 3, which, as above noted, is preferably of the composite construction hereinbefore described, is perforated somewhat closely so that it takes the form of a grid of substantially fine mesh. A second collar 13 upon the post 6 forms the support for the anode 2, preferably in the form of a wire grid and shaped with respect to the cathode 3 so as to give a substantially uniform distribution of its active surface withrespect to the active surface of the cathode 3. In Fig. 5 of the drawing both the anode 2 and the cathode 3 are, for the sake of simplicity of illustration, shown in grid form only in part, it being understood however that the entire electrodes are preferably of the grid construction above described. A suitable conductor 14 extending through. the pillar 11 serves to connect the cathode 3 with the exterior electrical circuit and a conductor 15 connects the anode 2 to the other side of the circuit through a suitable current limiting resistance unit 9 mounted within the hollow pillar 11. The space at the base of the vessel 1 and surrounding the pillar 11 forms a reser-v Voir or container for a metal 8 similar to the metal forming the active surface of-the electrodes, such as for example, potassium or The member 7 ispreferably made of glass.

The gaseous content of the vessel 1 may be any one of the gases of the argon group and we have found that one of the gases, such as neon, slightly diluted with another gas of this group, such as helium, functions advantageously as Will be hereinafter made clear. After the luminous discharge has been started the metallic particles which are segregated from the electrodes, principally from the cathode, are discharged-against the member 7 Which, being interposed betweenthe electrodes and the greater portion of the interior surface of the vessel 1, intercepts such particles and prevents their being precipitated upon the walls of the vessel 1. The velocity of such particles is sufficient to heat the glass intercepting member 7 by their impact'thereon to such an extentthat such particles cannotadhere thereto and hence cannot form an opaque coating upon the member 7 itself. The precipitation of metallic particles from the cathode may also be diminished by the addition to the gaseous content of neon,

. for example, of any other gas of the argon group, helium for example, by means of which the velocity of the ions and of the metallic particles segregated from the electrodes is effectively diminished. The addition to the gaseous neon content of small volumes of-hydrogenmay cause similar beneficial results in reducing the precipitation of electrode particles. Such a dilution of the neon content with another gas also results in lowering the starting voltage of the lamp. It has also been foundthat the presence of potassium sub-hydride (KH) atthe cathodefunctions similarly to reduce the starting voltage as well as the precipitation. of elec- "trode particles.

' ance unit 9 causes the vaporization of the The energy dissipated in heat in the resistmetal 8 in the reservoir and the vapors therefrom constitute asupply of metal to replenish the material of the cathode, which undergoes a substantial deterioration by reason of the segregation therefrom of the small particles during the operation of the lamp and as heretofore described. The particles dis- I charged from the electrodes and intercepted by the member 7 fall into the reservoir at the base of the vessel 1 where they are combined with the supply of metal therein and function to replenish the metal of the cathode, thus going through a complete cycle. Due to the vaporization of the metal 8 in the reservoir at the base of the vessel 1, the vapors thereof will extend within reach ofboth the anode 2 and the cathode 3 upon which the particles in the vapor will be deposited. While we have illustrated the employment of the current limiting resistance 9 as a source of heatfor-vaporizin the metal 8 in the reservoir, it will be un erstood that the means for heating the metal 8 in the reservoir to vaporize the replenishing supply of electrode material is only illustratively set forth.

Some f the particles intercepted or reflected by the member 7 are cast upon the surface 10 formed by the collar 12 and upon the cylindrical surface 10 of the post 6 intervening the collar 12 and the collar 13. Such particles form upon this surface a conductive coating which functions to assist in initiating the starting of the lamp. This coating, formed after a relatively short period of operation of the lamp, constitutes an extension pf the cathode 3 in the direction toward the anode 2, thus diminishing the distance betweenthc two electrodes and initiating the ionization of the gaseous contentof the lamp, particularly in the regions intervening the two electrodes, to facilitate a more rapid starting of the entire discharge between the two electrodes.- -The collar 13 prevents the formation of this coating to an extent sufiicient to reach the anode 2 and thus to short-circuit 'the two electrodes, since no particles reflected from the member 7 are precipitated upon the under side of the collar 13.

The construction hereinbefore described is particularly adaptable for use in connection with a direct current source of current but such constructions are readily adaptable to alternating. currents. Thus, both electrodes may be made similar, in which instance both electrodes are preferably made in accordance with the construction of the cathode hereinbefore described.

It will thus be noted that there has been.

provided in this invention a gaseous conduction lamp in which the several objects of this invention heretofore noted as well as others are achieved and in which many advantages are attained.

As many possible embodiments may be made of theabove invention and as various changes mightbe made in the embodiment above set forth, it is to be understood that all matter herein set forth is to be interpreted as illustrative and not in a limiting sense.

We claim:

1. In a device of the class described, in I combination, a vessel having a gaseous content at relatively low pressure, a pair of electrodes mounted within said vessel one of which is subject to deterioration by the discharge therefrom of electrode particles, a

reservoir containing metal of which said one electrodeis formed, and means forvaporiz ing the metal within said reservoir to re plenish said electrode comprising a currentlimiting resistance in circuit with one of said electrodes and thermally related tosaid reser- 2. In a device of the class described, in combination, a vessel having a gaseous content at relatively low pressure, a pair of electrodes mounted within said vessel one of which is subject to deterioration by the discharge therefrom of electrode articles, a reservoir containin metal of WlllGll said one electrode is formed, and means including a current-carrying resistance unit for vaporizing the metal within said reservoir to r eplenish said electrode,

3. In a device of the class described, in combination, a vessel having a gaseous content at.low pressure, an electrode mounted=- within'said vessel and havin the form of a predetermined character suc as a letter ofthe alphabet, and a second electrode mountedwithin said vessel having its effective sur-' 15 face uniformly "distributed with respect to said first electrode, whereby said electrodes are adapted to maintain a luminous discharge therebetween in the form of said predetermined character, one of said electrodes being constructed so that said luminous discharge is substantially unobstructed to view as the deviqa isviewed in a direction from one elec{ trode toward the other. i 4. In a devicegof the class described, in combination, a vessel having a gaseous content at relatively low pressure, a pair of electrodes mounted within said vessel, said electrodes having an active material composed of 'a strongly electro-positive metal and thereby adapted to maintain a luminous discharge through said gaseous content at relatively low voltage, and means operable in response to heat produced by energy supplied to said electrodes for supplying said' eleci.3 5.tl0des with'electrode material to compensate for their deterioration.

5. In a device of the class described, in combination, a' vessel having a gaseous content at relatively low pressure, a pair of electrodes mounted within said vessel and subject to deterioration by the discharge therefrom of electrode particles, a reservoir containing metal of which said electrodes are formed,and heating means operated from the same source that supplies energy to said .electrodes for vaporizing the metal within said reservoir to replenish said electrodes.

6. In a device of the class described, in combination, a vessel having a gaseous: content at relatively low pressure, a pair of electrodes mounted within said vessel for maintaining a luminous discharge through said gaseous content,'and means formed by the precipitation of particles from said electrodes and forming an electrical extension of one electrode in a direction toward the other for producing an initial ionization of said gaseous content.

7. In a device of the class described, in combination, a vessel having a gaseous con tent at relatively low pressure, a pair of electrodes mounted within said vessel for electrodes are on one side thereof and the interror wall of said vessel is substantially j uxtaposod to the other side of said shield for intercepting electrode particles emanating from said electrodes and thereby preventing the'precipitation of said particles upon the interior wall of said vessel.

8. In a device of the class described, in combination, a translucent vessel having a gaseous content at relatively low pressure, a

pair of electrodes mounted within said vesscl formaintaining aluminous discharge- OTTO SCHALLER. FRITZ SGHROTER.

maintaining a luminous discharge through 

